The evolution of integrated circuit designs has resulted in higher operating frequency, increased numbers of transistors, and physically smaller devices. This continuing trend has generated ever increasing area densities of integrated circuits and electrical connections. The trend has also resulted in higher packing densities of components on printed circuit boards and a constrained design space within which system designers may find suitable solutions. Physically smaller devices have also become increasingly mobile.
At the same time, wireless communication standards have proliferated as has the requirement that mobile devices remain networked. Consequently, many mobile devices include a radio transceiver capable of communicating according to one or more of a multitude of communication standards. Each different wireless communication standard serves a different type of network. For example, a personal area network (PAN), such as Blue Tooth (BT), wirelessly maintains device connectivity over a range of several feet. A separate wireless standard, such as IEEE 802.11a/b/g (Wi-Fi), maintains device connectivity over a local area network (LAN) that ranges from several feet to several tens of feet.
A typical radio transceiver includes several functional blocks spread among several integrated circuit packages. Further, separate packages often each contain an integrated circuit designed for a separate purpose and fabricated using a different process than that for the integrated circuit of neighboring packages. For example, one integrated circuit may be largely for processing an analog signal while another may largely be for computationally intense processing of a digital signal. The fabrication process of each integrated circuit usually depends on the desired functionality of the integrated circuit, for example, an analog circuit generally is formed from a process that differs from that used to fabricate a computationally intense digital circuit. Further, isolating the various circuits from one another to prevent electromagnetic interference may often be a goal of the designer. Thus, the various functional blocks of a typical radio transceiver are often spread among several die packaged separately.
Each package has a multitude of power, ground, and signal connections which affects package placement relative to one another. Generally, increasing the number of electrical connections on a package increases the area surrounding the package where trace routing density does not allow for placement of other packages. Thus, spreading functional blocks among several packages limits the diminishment in physical size of the radio transceiver, which in turn limits the physical size of the device in which the radio transceiver is integrated.